$X_t = \phi X_{t-1} + \epsilon_t, X_0 = 0$ and $|\phi|<1$,
where $\epsilon_1,\epsilon_2, \cdots$ are all independent N(0,1).
like i know if $X_t$ can reach any subspace in one step then it is aperiodic, but Im very unsure on how i go about showing this..